Centrifugal model tests on toppling deformation of counter-tilt layered rock slopes based on change of slope angle

Based on the understanding of the effects of changes in the critical conditions on toppling deformation slopes, taking the toppling deformation slope of Gushui hydropower station of the Lancang River as the prototype, and by simulating the deformation evolution and failure process of counter-tilt layered slopes under different slope angles through centrifugal tests on three sets of slope models with different slope angles, the relationship between the change of the slope angle and the development of the toppling deformation is obtained. The results indicate that the toppling damage of the counter-tilt slope occurs first at the foot of the slope and then develops upward. The larger angle will shorten the cumulative time required for deformation. The evolution process of the toppling deformation of the counter-tilt layered rock slope can be divided into 4 stages: (1) The rock body of the slope falls, and its trailing edge settles. (2) The rock at the bottom of the slope is broken, and the "toppling and bending" deformation occurs. (3) The broken zone extends from the bottom to the top of the slope, and the rock at the top of the slope is damaged by tension. (4) The broken zone extends until it is coalescent, and the "toppling and breaking" deformation occurs. If other conditions remain unchanged, the steeper slopes have a greater range of toppling deformation and are more likely to produce multi-stage broken zones during dumping, and the energy that causes the slope damage is released multiple times. Changing the angle of the slope can lead to differences in the final destabilization pattern. The smaller the slope angle, the more likely the deformed slope of the dump will evolve into an overall slip instability, and the steep slopes are more likely to collapse after toppling.